package 第1节循环语句;

import java.util.Scanner;

public class AnLi08 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        double sum = 0;    //正数的和
        int count = 0; //正数的个数
        for (int i = 0; i < n; i++) {
            int num = input.nextInt();
            if (num <= 0) {
                continue;
            }
            sum += num;
            count++;
        }
        System.out.println(sum / count);
    }
}